The invention relates generally to a method for suitably positioning light waveguides for joining the light waveguides in a fiber-to-fiber coupling location. The coupling ends of the fibers, hereinafter referred to as function fibers, to be coupled are respectively aligned and fixed on a carrier element. The invention is also directed to a coupling element for a light waveguide switch.
When joining light waveguides in coupling locations such as found, for example, in light waveguide switches, an exact alignment of the optical axis and a slight spacing between the end faces of the light waveguides are critical. Otherwise, transmission losses occur at the coupling location due to mechanical maladjustment. Losses can be distinguished with regard to two factors: (1) a radial offset of the optical axes due to an axial spacing of the fiber end faces, and (2) an angular error between the optical axes.
For aligning the light waveguides at coupling locations, especially in releasable plug type connections, known methods require extremely involved and exact fitting component parts which have bores that align more or less well with one another. Glass fibers are aligned and fixed in these bores. In the manufacture of non-releasable or switchable coupling locations, there is an attempt to achieve an alignment of fibers with high precision devices having exact guides and fine adjustments. German published application No. 31 38 686, discloses such a device. In such switches, the fibers usually have their coupling ends placed on the respective stationary and movable carrier elements and they are aligned as precisely as possible relative to one another, afterwhich they are glued in place. This procedure is disclosed, for example, in German published application No. 33 35 673. These known methods exhibit fundamental difficulties when utilized for mechanical switchable coupling locations wherein one fiber is to be selected to be coupled to one or more additional fibers. This difficulty results because when the fibers are to be mounted in an apparatus, they can be aligned in only one switch position. This method precludes any involved adjustment of the already fixed fibers for other switch positions.
Therefore, it is an objective of the present invention to develop a joining method which can be utilized without precise apparatus or involved adjustment in the mounting of light waveguides in fiber-to-fiber coupling locations for use in devices as discussed above. The method of the present invention avoids angular errors and axial offset and keeps the distance between the fiber end faces at a minimum. This enables a compensation of core eccentricities and results in acceptable component tolerances. The invention may also be utilized for a coupling element of a light waveguide switch which also has these advantages.